Cation exchange resin



United, States Patent F CATION EXCHANGE RESIN Karl Haagen,Leverkusen-Bayerwerk, Germany, assignor to Farbenfabriken BayerAktiengesellschaft, Leverkusen, Germany, a corporation of Germany NoDrawing. Application March 5, 1952, Serial No. 275,011

The present invention relates to cation-exchange resins and moreparticularly to cation-exchange resins containing groups of diiferentacidity, preferably sulfonic acid and carboxylic acid groups, and toprocesses of producing such exchange resins.

In my co-pending application Ser. No. 210,793 filed February 13, 1951,now U. S. Patent No. 2,692,866 I have described cation-exchangersproduced from ethers of aromatic hydroxy compounds. These exchangeresins contain as active groups either sulfonic or carboxylic acidgroups. They are obtained by condensing in an acid medium aldehydes orsubstances yielding aldehydes and ethers of aromatic monoor polyhydroxycompounds wherein preferably all the hydroxy groups are etherified, saidethers containing already the active groups for ion exchange and/ or theactive groups being introduced with the aldehydes. Condensation ispreferably carried out in a strongly acid medium at temperatures up to115 C. An especially suitable aldehyde is formaldehyde. The processaccording to the invention may also be performed by precondensing theabove ethers with aldehydes, for instance, benzaldehyde, that maycontain the active groups for ion exchange, such as, for instance,benzaldehyde disulfonic acid or acetaldehyde disulfonic acid.

By drying the gels at 100-120 'C., after washing in the usual manner,substantially cross-linked condensation products are obtained which, asto their insolubility in water, are by no means inferior to thecompounds hitherto obtained from aromatic monoand polyhydroxy compounds,but which are far superior as to their stability to alkalies andoxidizing agents.

Suitable ethers for use in the process are ethers of aromatic mono orpolyhydroxy compounds in which the second ether component is ofaliphatic or aromatic nature, such as in the case of arylalkyl ethersand diaryl ethers. As examples may be mentioned anisol, diphenyl ether,phenoxy ethane sulfonic acid, and phenoxy acetic acid. The ether bridgemay also be a part of another nucleus, such as in the case, forinstance, of diphenylene oxide and diphenylene dioxide.

The ethers may sometimes contain small amounts of free hydroxy groups;the stability to alkalies and oxygen of the exchange resins preparedfrom the latter is not essentially reduced as compared with the resinsproduced from pure ethers. The cation-exchanging properties of theseresins in most cases meet with the practical demands.

- Examples of suitable active groups capable of forming salts withalkalies are, besides the sulfonic and carboxylic acid group,sulfonamide and cyanamide groups and nitroalkyl groups. The activegroups may be attached in the ethers to the aromatic nucleus eitherdirectly or via an aliphatic side chain. Arylalkyl ethers 'of particularusefulness are those in which the active groups are terminally. linkedto an alkyl radical, for instance, phenoxy acetic acid and phenoxyethane sulfonic acid. The active groups may also be introduced with2,729,607 Patented Jan. 3, 1956 ion exchange by sulfonating an aromaticether, condensation of the ether containing the sulfonic acid group withaldehyde may be performed in the sulfonation mixture. After gelformation the excess sulfuric acid is removed from the resin by washingwith water.

One object of the invention is to provide cation exchange resins havinga high cation exchange capacity which contain, besides etherifiedaromatic hydroxy groups, groups of diiierent acidities, preferablysulfonic and carboxylic acid groups.

Another object of the invention is to provide a process of producingsuch cation exchange resins.

Further objects will become apparent as the following descriptionproceeds.

It has been found that cation exchange resins containing etherifiedaromatic hydroxy groups and cation exchanging groups of differentacidities, such as sulfonic and carboxylic acid groups, may be producedby the process described in my copending application Ser. No. 210,793.

The new exchange resins, resistant to alkalies and oxygen, are producedby condensing, in an acid medium, ethers of aromatic hydroxyl compoundscontaining groups of difierent acidities, for instance sulfonic andcarboxylic acid groups with aldehydes or aldehyde yielding compounds.The exchange resins of the present invention may be further obtainedfrom at least two components capable of being condensed by aldehydesprovided that each of at least two of said components contains only one,but not the same kind of ion exchanging groups and at least one of saidcomponents contains one or more etherified aromatic hydroxy groups, andthat said components are condensed with aldehydes to form cross-linkedhydrogels which are hardened in the usual manner. It is within the scopeof the invention to employ in the production of cation exchange resinsthe starting materials obtained by condensing 1 mol of an aldehydecarboxylic acid and 2 mols of an aromatic sulfonic acid containing atleast one etherified phenolic hydroxyl group, or by condensing 2 mols ofphenoxy acetic acid and 1 mol of benzaldehyde disulfonic acid whichcondensation gives rise to the formation of a triphenyl methanederivative of the following structural formula:

0cm coon G Ooorn coon HOsS Examples of further suitable startingmaterials for the production of exchangers according to the inventionare, for instance, mixtures containing phenoxy acetic acid and thesulfonic acid of a polycyclic hydrocarbon or of an aromatic ether, likefor instance diphenyl ether and anisol, or of a cyclic ether, like forinstance diphenylene oxide or diphenylene dioxide. It may sometimes beof advantage to previously condense both components separately withaldehyde and then to mix the resulting higher molecular weightcondensation products in form of their viscous solutions and to form agel by subjecting the combined solutions to after-condensation. Whenstarting from components of different reactivity to aldehydes it isadvantageous to condense the lesser reactive component with aldehydebefore mixing same with the other component.

The new cation exchange resins may successfully be used for carrying outthe well-known exchange reactions,

HOsS

turther nor .asadsorbentsior purifying liquid and gaseous systems. Theyare particularly suited for simultaneously removing hardness andbicarbonate ions from boiler feed water by the process of acid-saltregeneration.

, The. f low ngv examp es illus rate some ways of Pr paring suitablecation exchange resins. However, the. nven n ;is not limi ed toth seproced res but m y th r i e p cticed within the c pe of. the appendedclaims, the parts given in the examples being by weight.

Example 1 848 parts of the. sodium salt of benzaldehyde disulfonic acid(containing 62.7 per cent calculated on the molar Weight 266) and 80.0parts of phenoxy acetic acid (containing 92.3 per cent calculated on themolar weight 15.2) are .introdu edinto 1.00.0v parts of 70 per centsulfnric acid at 90-100 C. After about half an hours tirring a turther4.3.5 parts of pheno s) acetic c are added When thcfcondeufiation. iscomplete the mixture is allowed to cool; thereupon 1200 parts of 3.0 percent formalin are. added to the mixture which is heated to 100 C. Theclear solution Oon becomes more viscous and solidifies to a homogeneoushydrogel which after about 20 hours is heated in a closed vessel to 100C. and subsequently dried at 110 C. The yield amounts to 2495 parts ofxerogel which is ground, sifted and introducedinto a 20 per cent sodiumchloride solution for swelling. The salt solution is gradually dilutedwith water and finally entirely displaced by Water. The exchanger isstable to hot alkaline water, shows a high exchanging capacity and isparticularly suited for removing hardness and bicarbonate ions fromboiler feed water.

Example. 2

700 parts of naphthalene are sulfonated with 800 parts of sulfuric acidmonohydrate at 160 C. After cooling to about 100 C. the sulfonationmixture is introduced with stirring into a suspension of 2715 parts ofphenoxy acetic acid of 83.9 per cent strength in 4600 parts of formalinand the reaction mixture is heated to about 85 C. The reactiontemperature rapidly increases. The heat evolved in the exothermiccondensation reactions causes an intense boiling of the solution whichgradually becomes more viscous and finally solidifies to a homogeneousclear gel. The product is heated in a closed vessel to 95 C. for about24 hours and thereafter dried in the air at 110 C. for 3-4 days. 3900parts of xerogel are obtained which is ground, sifted and swelled asindi cated in Example 1.

The ratio of naphthalene sulfonic acid to phenoxy acetic acid may bevaried over a fairly wide range so that any desired proportion of theactive groups can be easily controlled in the condensation mixture.

Example 3 500 parts of technical aeenaphthene are heated with 500 partsof 100 per cent sulfuric acid to 145 C. for 6 hours. After cooling toabout 100 C. the suspension mixture is introduced with stirring into asuspension of 427 parts of 88.9 per cent phenoxy acetic acid in 1200parts of 30 per cent formalin. While the temperature of the mixturegradually increases, the phenoxy acetic acid is completely dissolved;The solution becomes morev viscous with ini g mpera ur and fter addi g.60 p rt o p aformaldehyde presently solidifies to a dark, clear gel. The

V gel is heated in a closed vessel to 8590 C. for 12.-1,6

hours and subsequently dried in the, air at 110 C. for 2 days. The yieldamounts to 1585. parts of dried resin which is ground and swelled inwater. The exchanger is excellently suited for removing hardness andbicarbonate ions from water.

I claim:

h p s of pr d c nga er nsol ble c ti n exchanging resins which comprisescondensing in an acid me iu at l v mp rature ar matic compoun capable ofcondensing with formaldehyde which compounds contain sul'fonic acid andcarboxylic acid-groups but substantially no freephenolic groups, and atleast one of which contains a phenolic group etherified with a member ofthe class consisting of aromatic and aliphatic compounds, with acompound selected from the group consisting of formaldehyde andformaldehyde yielding substances, continuing condensation to form a geland dryniatic. compound containing a sulfonic acid group is a ulfionatedaromatic hydrocarbon.

6;. The process according to claim 1., wherein one of the aromaticcompounds used contains an aldehyde group which is reacted with at leastone of the other aromatic compounds, whereafter the reaction productobtained is condensed with a compound selected from the group consistingof formaldehyde and. formaldehyde yielding substances.

7. The process according to claim 6, wherein the aromatic compoundcontaining an aldehyde group is a benzaldehyde containing at least onesulfonic acid group.

8. The. process according to claim 6, wherein the aromatic. compoundcontaining an aldehyde group is a benzaldehyde containing atv least onecarboxylic acid group.

9. The. process according to claim 6, wherein the aromatic compoundreacted with the aldehyde is an aromatic sulfonic acid containing atleast one etherified phenolic hydroxyl group.

10. The process according to claim 6, wherein the aromatic compoundreacted with the aldehyde is phenoxy acetieacid.

1.1..A water insoluble cation exchanging solid resin consisting of anaromatic formaldehyde condensation product containing carboxylic. andsulfonic acid groups and phenolic. hydroxy groups which are etherifiedwith a member of the class consisting of aromatic and aliphaticcompounds, said resins being substantially free of unetherified phenolichydroxyl groups. 7

12. A water insoluble cation exch ging s li r n accordin to claim .11containing a phenoxy acetic acid group.

.13... A water insoluble ca ion exchang o resin esul ingtrom. theProcess. of claim. .1.

.14. process. of removing cations from a liquid medium which comprisescontacting such medium with a cation exchanging resin obtained by theprocess of claim 1.

References Cited in the file, of this patent UNITED STATES PATENTS2,191,853 Holmes n- Feb. 27, 1940 2,259,503 Wasseneger Oct. 21,1941

2,319,359 Wasseneger Mar. 18, 1943 FOREIGN PATENTS 952,068' France vApr. 25,1949

829,498 Germany Jan. 28,1952

OTHER REFERENCES Lautsch: Di Chernie, vol. 57, pages149-154 (.1944).Gortner et..e1 Outlines of, Biochemistry 3d ed., .1949, Pages 74.2. to745, 7.51 to 753. V

.Br uus; Pap r. Trade Journa 31, 1940, pag 3.3.and. 37.

11. A WATER INSOLUBLE CATION EXCHANGING SOLID RESIN CONSISTING OF ANAROMATIC FORMALDEHYDE CONDENSATION PRODUCT CONTAINING CARBOXYLIC ANDSULFONIC ACID GROUPS AND PHENOLIC HYDEOXY GROUPS WHICH ARE ETHERIFIEDWITH A MEMBER OF THE CLASS CONSISTING OF AROMATIC AND ALIPHATICCOMPOUND, SAID RESINS BEING SUBSTANTIALLY FREE OF UNETHERIFIED PHENOLICHYDROXYL GROUPS.